1. Field of the Invention
The field of the invention is that of time-accounting systems and devices, and notably that of time-accounting devices for reckoning periods of parking regulated by rules.
More precisely, the present invention relates to a device that can be used to check the authenticity of a device of this type.
The term "time-accounting device" refers to an apparatus constituted, for example, by a box, preferably a portable one, that is designed to be placed behind the windscreen of a vehicle and works in cooperation with a prepaid electronic ticket, for example a memory card, to decrement fee units, memorized in the card, according to the parking time. This type of device can be used to eliminate the need for fixed individual posts (of the pavement parking meter type) or posts used in common by many vehicles (of the type installed at the entrance to parking lots). The user automatically pays the parking fees by introducing a prepaid memory card into his box. The boxes are generally sold, loaned or given out on hire by local authorities or their agents who sell parking units in the form of cards of a different type for each local authority. The validity of the parking can be verified by means of a display device on which there appear various elements of information needed by the checking staff, for example the number of the parking zone selected by the user, a code identifying notably the type of card introduced by the user into the box and representing the town or city in which the parking is being done and, as the case may be, an information element indicating a state of infringement of the rules, and the number of fee units still available in the card. The memories of the cards may be either rewritable or irreversibly written.
2. Description of the Prior Art
A device such as this is described, for example, in the French patent No. 87/06776 filed on behalf of the SOCIETE INTERNATIONAL POUR L'INNOVATION. The device described is a box comprising means to managing the changing of cards inserted into the box. It also includes means enabling the resetting of a clock internal to the box. This clock serves notably to make a regular count of the fee units and to take account of periods during the day when it is not necessary to pay for parking.
A major preoccupation over this type of device relates to the need to detect fraudulent individuals who might use boxes that have not been distributed by the rightful authorities. Indeed, fraudulent individuals may think of making boxes that have the same external appearance as authentic boxes but contain only a display unit cooperating with appropriate electronic circuitry to simulate a counting of fee units. It would then be impossible for a checker to detect the fraud without dismantling the spurious box.
An object of the present invention, notably, is to overcome this drawback of the prior art.